#33901: non-deterministic collations doesn't work with Unique=True on
Postgres13.3
-------------------------------------+-------------------------------------
Reporter: Ed Chai | Owner: Ed Chai
Type: Bug | Status: new
Component: Migrations | Version: dev
Severity: Normal | Resolution:
Keywords: collation unique | Triage Stage: Ready for
citext | checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by kenneweg):
* status: closed => new
* resolution: fixed =>
Comment:
the issues can be recreated as follows:
I have an old migration that sets the field with unique=true
I have a new migration that sets the field with unique=true,
db_collation="utf8_unicode_ci"
The old migration runs first, and creates a LIKE index for the field. The
new migration attempts to run:
{{{
django.db.utils.NotSupportedError: nondeterministic collations are not
supported for operator class "varchar_pattern_ops"
}}}
My work around is writing a DROP INDEX of the LIKE index that is created
by the first migration
{{{
migrations.RunSQL(
sql="DROP INDEX IF EXISTS
appname_modelname_fieldname_073c92ac_like;",
reverse_sql=migrations.RunSQL.noop,
),
migrations.AlterField(
model_name="modelname",
name="fieldname",
field=models.CharField(
blank=True, db_collation="utf8_unicode_ci",
max_length=255, null=True, unique=True
),
),
}}}
But this is quite messy.
--
Ticket URL: <https://code.djangoproject.com/ticket/33901#comment:18>
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